This invention relates generally to brush seals and more particularly to a brush seal for use in gas turbine engines.
A gas turbine engine operates according to well known principles wherein an incoming stream of atmospheric air flows through the engine along an axially extending flow path. At least a portion of the incoming air is compressed in a compressor section of the engine and then mixed with fuel and burned in a combustor section to produce a high energy, high temperature exhaust gas stream. The hot gas stream exits the combustor and subsequently passes through a turbine section that extracts energy from the exhaust gas stream to power the compressor and provide useful work such as powering an aircraft in flight. The turbine section typically includes a stationary turbine nozzle disposed at the outlet of the combustor for channeling combustion gases into the turbine rotor disposed downstream thereof.
Uncontrolled leakage of gasesxe2x80x94such as atmospheric air, exhaust gases, or otherxe2x80x94within the engine contributes to a reduced engine efficiency. Seals are used to control this energy loss by interposing them in a leakage path to reduce the volume or mass of gas passing from one part of the engine to another. The so-called E-seals or W-seals are commonly used in gas turbine engines for sealing between static components. One such location that is particularly difficult to seal is the interface between the combustor and the turbine nozzle due to the high relative movement and high temperatures in the region. Brush seals can withstand the high relative movements in the radial and axial directions and therefore are good candidates for sealing this interface. Double brush seals are particularly good candidates because they are capable of sealing both the combustor and the turbine nozzle.
A typical double brush seal includes at least two seal stages with each stage including a bristle pack having a plurality of bristles. The bristle pack of each stage is disposed between a front plate (i.e., a plate facing a higher pressure) and a back plate with adjacent stages being spaced apart a specified distance. The fixed ends of the bristles are usually attached to one engine part, and the free ends of the bristles are disposed in sealing engagement with a sealing surface on another engine part. Brush seals are not intended to function so as to completely seal one engine section from another, but rather rely upon the tortuous flow path created between the bristles to reduce gas flow therethrough and to control the pressure drop between the engine sections. Typically, the leakage flow and pressure drop are in the same direction for each stage of the brush seal.
Although a good candidate for sealing the combustor-turbine nozzle interface, conventional double brush seals can be difficult to install at that location because of the spacing between the stages and because each seal stage requires two plates. The multiple plates also increase the cost and weight of the sealing arrangement.
Accordingly, there is a need for a double brush seal for sealing the combustor-turbine nozzle interface of a gas turbine engine that is relatively easy to install and uses fewer parts than conventional double brush seals.
The above-mentioned need is met by the present invention which provides a brush seal for sealing the combustor-turbine nozzle interface of a gas turbine engine. The brush seal comprises a stationary support member and an intermediate plate attached to the stationary support member. The brush seal also includes a first end plate located upstream of the intermediate plate and attached to the stationary support member, and a second end plate located downstream of the intermediate plate and attached to the stationary support member. A first bristle pack is disposed between the first end plate and the intermediate plate, and a second bristle pack is disposed between the second end plate and the intermediate plate.
The present invention and its advantages over the prior art will become apparent up)on reading the following detailed description and the appended claims with reference to the accompanying drawings.